I have a list in front of me from my Naturopath with lists of cleansing foods for the liver and gallbladder, apple juice is #1 on the list (of course it is in alphabetical order :)
Other liver and gallbladder healing foods include: apricots, beet greens, bran, Brewer's Yeast carrot juice, dandelion greens, gooseberries grapefruit, grapefruit juice, grape juice, lemon juice, nuts, olive oil, orange juice, pears, rhubarb, soybean lecithin, squash, sunflower seeds, vinegar, walnuts and water. This also says that Chamomile tea will help dissolve gallstones. Here is a quote from the article:"Lemon juice is so powerful it can stimulate, purge and empty the gallbladder, says one doctor, who recommended 3 tablespoons of undiluted unsweetened lemon juice 15-30 minutes before breakfast daily for a week."
Another quote:"Grapes help combat liver disorders, jaundice and stimulates bile flow. They have been recommended to relieve a sluggish liver, with pain and tenderness on the right side-in a meat and grape juice diet (white meat chicken without the skin)..." the page ends there.
Hopefully this list will help you decide what to eat while you are preparing to flush. For some, these foods might help when they cannot flush. I don't have the name of the article or the author; its just a copy my doctor gave me.

Apples are very good and have a double action. They are highly recommended either fresh, juiced, stewed or as apple cider vinegar. The malic acid in apples is reported as helping to soften stones and is often used as a preparation for a liver flush. The pectin found in apples binds to the cholesterol in the bile which is then passed out as faecal matter. This makes the liver produce fresh bile which appears to have a cleansing action on the biliary system and also reduces blood cholesterol level.

Telman